This invention relates to the field of pull-type farm implements and, more particularly, to a swivel hitch arrangement that allows the towing tractor and tongue of the pulled implement to be turned at relatively sharp angles relative to one another without adversely affecting the transmission of mechanical driving power from the power take-off shaft of the tractor to driven components of the implement.
Various types of swivel hitches are presently known. Some are designed for use with the lower links of the three point hitch of a conventional tractor, while others are designed to be connected to the draw bar of the tractor. Conventional draw bar swivel hitches often require the user to first bolt on a special adaptor to the draw bar before the implement can be hooked to the adaptor and readied for operation. Tools must be used to attach the adaptor, and time must be taken to complete the process that could otherwise be used for more advantageous purposes. Moreover, currently available draw bar swivel hitches are complex and do not necessarily distribute draft forces in the optimum manner.
The present invention contemplates a swivel hitch that permits the towed implement to be hitched to the tractor draw bar rather than the three point hitch. No adaptor must be attached to the draw bar, and, once the hitch has been initially adjusted for the particular draw bar at hand, no tools are thereafter required in order to establish a fully hitched condition between the implement and the draw bar. In a preferred form, a pair of stacked gear boxes, the lower one of which can swivel relative to the upper, are completely isolated from draft loads exerted between the tractor and the implement. Moreover, such draft loading is, in the preferred embodiment, distributed to a pair of separate locations, rather than concentrated in one central region as in certain conventional constructions.
A draw bar swivel hitch in accordance with the present invention has an upper right angle gear box that is fixed to the tongue and a lower right angle gear box that swivels relative to the upper gearbox about an upright axis. A hitch is pivotally attached to the tongue for horizontal swinging movement about the upright axis of the swivel gear boxes, and such hitch has a receiver at its lowermost end provided with a forwardly facing draw bar socket. The draw bar socket is adapted to rather loosely receive the rearwardly extending draw bar of the towing tractor such that, when fully received within the socket and retained therein by a king pin or the like, the draw bar can pivot up and down about a transverse pivot within a limited range of motion and can also rotate to a limited extent about a fore-and-aft axis through the socket, thus accommodating the necessary pitching and rolling action between the tractor and the implement. The hitch is operable to swivel the lower gear box to the extent necessary to keep its input shaft always in line with the power take-off shaft of the towing tractor. In a preferred embodiment, a pair of laterally spaced, rearwardly extending arms embrace the lower gear box on opposite sides thereof to effect the necessary steering action, but no draft loads are imparted to the lower gear box because all such loads are transmitted through a pair of upper and lower, vertically spaced pivots between the hitch and the tongue at locations above and below the gear boxes respectively.
An alternative embodiment, which is more of a xe2x80x9cpull-throughxe2x80x9d style, retains the upper pivot between the hitch and the tongue but removes the lower pivot in favor of a secure connection between the lower gear box and the hitch, thus causing a measure of the draft loading to be applied to the lower gear box.
Because no tools are required for securing the connection between the draw bar and receiver of the hitch, the user can quickly and easily hook up the implement in the first instance, and just as easily unhook the implement when operations are finished.